The present invention relates to a coin sorting device which can be mounted in an automatic vending machine and which is capable of facilitating detection of a sensor abnormality and of shortening the adjustment time.
FIG. 6 schematically illustrates the construction of an electronic coin sorting device. As shown in the figure, when a coin 1 is introduced, the coin 1 rolls down a coin path 2 and is assessed as either good or bad, and has its denomination read by the coil sensor which is disposed on the coin path 2. The coin that is assessed as good is led to a good coin path 5A as a gate 4 is pulled. If the coin is assessed as bad, the coin is led to a bad coin path 5B as the gate 4 is not pulled.
FIG. 7 is a construction diagram depicting the principles of the detection circuit 11 used to detect a change in the impedance of the coil sensor when the coin 1 passes the coil sensor 3; comprising a bridge circuit consisting of the coil sensor 3, resistors 6A and 6B, a capacitor 7, and an oscillator 8. The output of this bridge circuit is supplied to a rectification circuit 10 through a differential amplification circuit 9. When the coin 1 is introduced into the coin sorting device, the output 11a of the detection circuit 11 changes with the characteristics of the coin 1 as shown in FIG. 8 (1A through 1C).
FIG. 5 is a block diagram of a circuit for making adjustments and determinations in a conventional coin sorting device. With this system, when the coin sorting device is adjusted, the analog output value 11a that is derived from the detection circuit 11 in FIG. 7 as a result of introducing a coin with a reference characteristic, is converted into a digital value "x(t)" by means of an A/D converter 12. Furthermore, a peak value "x" is obtained from this digitally converted output "x(t)" by means of the peak detector 13, and this peak value is then adopted as a characteristic value. This characteristic value is stored in the memory 14 as the reference value for a denomination.
Next, when the coin sorting device is actually used to sort coins, the characteristic value of the introduced coin is compared, using a comparator 15, with the reference value stored in the memory 14, and if the difference between these two values is within a permissible range, the coin will be determined, by a determination circuit 16 to be a good coin of the denomination corresponding to the reference value.
In the above-mentioned conventional coin sorting device, the reference value stored in the memory 14 is the characteristic value of a coin introduced during an adjustment. When the coil sensor 3 suffers from any abnormality, the characteristic value detected by this abnormal sensor will be used as the reference value; and it will be impossible to detect any abnormality in the coil sensor 3.
The present invention is aimed at providing a coin sorting device capable of facilitating detection and/or compensation of a sensor abnormality and of shortening the adjustment time.